CHICAGO (AP) — Young people have made up the largest percentage of new confirmed cases of the coronavirus in Chicago in recent weeks.

City officials warned Wednesday that the trend could lead to the closure of bars or other types of businesses. City health data shows that 29% of confirmed coronavirus cases since June 15 have been among people ages 18 to 29.

Earlier this year it overwhelmingly affected older people. Also, Wednesday, Gov. J.B. Pritzker’s administration re-released guidelines indicating when commerce and other social interaction might need to be curbed again because of a surge in various regions of the state.